As is known, motor vehicle wheels, particularly car wheels, are divided substantially into two categories: steel wheels and light alloy wheels.
Light alloy wheels have a higher performance than steel wheels and generally have a better aesthetic finish.
The production cost of the light alloy wheels is also higher than that of steel wheels.
Steel wheels are generally covered by a wheel cover for concealing at least partially from sight the hub and the spokes that connect the hub to the rim, and have a protective and aesthetic finishing purpose.
Such wheel covers are made of plastics and are fixed to the rim of the wheel by means of peripheral clips; said clips allow both easy coupling of the wheel cover to the wheel and easy removal therefrom.
When it is necessary to change a tire due to a puncture, it is generally necessary to remove the wheel cover and act on the bolts (the screws for fixing the hub of the wheel to the axle are commonly known as “bolts” although they are not associated with a nut).
However, the ease with which said wheel covers can be removed from the wheel leads to two problems: a first problem is linked to easy theft of the wheel covers and the second problem is linked to the real possibility of losing the wheel covers while the vehicle is moving.
It should also be noted that the aesthetic impression conveyed by such plastics wheel covers is of low quality.
The aesthetic enhancement that the wheels give to the buyer of a motor vehicle is instead very important: the possibility for a motor vehicle dealer to provide, as an accessory of the vehicle, wheels which have a pleasant appearance is in fact a very important commercial leverage point.
Motor vehicle dealers therefore seek to provide vehicles with wheels whose aesthetics is equal to that of light alloy wheels (even when the wheels are not required to have a performance comparable to that of light alloy wheels) while trying to reduce their costs.
In order to solve this problem, one solution has been to provide a wheel cover made of plastic material which has a layer of aluminum alloy metal on its exposed surface.
However, this solution entails a system for fixing the wheel cover to the wheel which is of a traditional type, by means of the so-called peripheral clips or also by coupling the bolts for fixing the wheel to the axle of the vehicle.
Perforated receptacles are in fact provided on the wheel cover, and the heads of the bolts abut against their bottom, thus locking the wheel cover in a sandwich-like fashion against the hub of the wheel.
It is evident that this solution does not solve the problem of the risk of loss or theft of the wheel cover in the case of fixing means such as peripheral clips, whereas if the bolts retain the wheel cover, in the long term the pressure of the bolts on the bottom of the receptacles causes the deterioration of such receptacles, with the real possibility of the formation of cracks and consequent breakage of the wheel cover.
Another solution, which however is limited to the case of light alloy wheels, entails the possibility to provide a wheel cover made of aluminum alloy with a surface finish which is superior to that of the wheel; said wheel cover matches exactly the shape of the hub and spokes of the wheel and is glued thereto, in practice so as to form a wheel in which the wheel cover is integrated.
This solution, if transferred to the case of steel wheels, is scarcely applicable, both due to the real risk of less than optimum bonding power of the adhesive used to fix the wheel cover and due to the need to provide the wheel and the wheel cover with exactly the same shape, entailing an increase in the production costs of wheels, which are generally standardized in their shape for each car model and are subsequently differentiated by the type of wheel cover applied.